RecoveryController.java revision 50bc7e42d73c9ca8d77dcd538619c6d6eeaf6dea
1/* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.security.keystore.recovery; 18 19import android.annotation.NonNull; 20import android.annotation.Nullable; 21import android.annotation.RequiresPermission; 22import android.annotation.SystemApi; 23import android.app.PendingIntent; 24import android.content.Context; 25import android.content.pm.PackageManager.NameNotFoundException; 26import android.os.RemoteException; 27import android.os.ServiceManager; 28import android.os.ServiceSpecificException; 29import android.security.KeyStore; 30import android.security.keystore.AndroidKeyStoreProvider; 31 32import com.android.internal.widget.ILockSettings; 33 34import java.security.Key; 35import java.security.UnrecoverableKeyException; 36import java.security.cert.CertPath; 37import java.security.cert.CertificateException; 38import java.security.cert.X509Certificate; 39import java.util.ArrayList; 40import java.util.List; 41import java.util.Map; 42 43/** 44 * Backs up cryptographic keys to remote secure hardware, encrypted with the user's lock screen. 45 * 46 * <p>A system app with the {@code android.permission.RECOVER_KEYSTORE} permission may generate or 47 * import recoverable keys using this class. To generate a key, the app must call 48 * {@link #generateKey(String)} with the desired alias for the key. This returns an AndroidKeyStore 49 * reference to a 256-bit {@link javax.crypto.SecretKey}, which can be used for AES/GCM/NoPadding. 50 * In order to get the same key again at a later time, the app can call {@link #getKey(String)} with 51 * the same alias. If a key is generated in this way the key's raw material is never directly 52 * exposed to the calling app. The system app may also import key material using 53 * {@link #importKey(String, byte[])}. The app may only generate and import keys for its own 54 * {@code uid}. 55 * 56 * <p>The same system app must also register a Recovery Agent to manage syncing recoverable keys to 57 * remote secure hardware. The Recovery Agent is a service that registers itself with the controller 58 * as follows: 59 * 60 * <ul> 61 * <li>Invokes {@link #initRecoveryService(String, byte[], byte[])} 62 * <ul> 63 * <li>The first argument is the alias of the root certificate used to verify trusted 64 * hardware modules. Each trusted hardware module must have a public key signed with this 65 * root of trust. Roots of trust must be shipped with the framework. The app can list all 66 * valid roots of trust by calling {@link #getRootCertificates()}. 67 * <li>The second argument is the UTF-8 bytes of the XML listing file. It lists the X509 68 * certificates containing the public keys of all available remote trusted hardware modules. 69 * Each of the X509 certificates can be validated against the chosen root of trust. 70 * <li>The third argument is the UTF-8 bytes of the XML signing file. The file contains a 71 * signature of the XML listing file. The signature can be validated against the chosen root 72 * of trust. 73 * </ul> 74 * <p>This will cause the controller to choose a random public key from the list. From then 75 * on the controller will attempt to sync the key chain with the trusted hardware module to whom 76 * that key belongs. 77 * <li>Invokes {@link #setServerParams(byte[])} with a byte string that identifies the device 78 * to a remote server. This server may act as the front-end to the trusted hardware modules. It 79 * is up to the Recovery Agent to decide how best to identify devices, but this could be, e.g., 80 * based on the <a href="https://developers.google.com/instance-id/">Instance ID</a> of the 81 * system app. 82 * <li>Invokes {@link #setRecoverySecretTypes(int[])} with a list of types of secret used to 83 * secure the recoverable key chain. For now only 84 * {@link KeyChainProtectionParams#TYPE_LOCKSCREEN} is supported. 85 * <li>Invokes {@link #setSnapshotCreatedPendingIntent(PendingIntent)} with a 86 * {@link PendingIntent} that is to be invoked whenever a new snapshot is created. Although the 87 * controller can create snapshots without the Recovery Agent registering this intent, it is a 88 * good idea to register the intent so that the Recovery Agent is able to sync this snapshot to 89 * the trusted hardware module as soon as it is available. 90 * </ul> 91 * 92 * <p>The trusted hardware module's public key MUST be generated on secure hardware with protections 93 * equivalent to those described in the 94 * <a href="https://developer.android.com/preview/features/security/ckv-whitepaper.html">Google 95 * Cloud Key Vault Service whitepaper</a>. The trusted hardware module itself must protect the key 96 * chain from brute-forcing using the methods also described in the whitepaper: i.e., it should 97 * limit the number of allowed attempts to enter the lock screen. If the number of attempts is 98 * exceeded the key material must no longer be recoverable. 99 * 100 * <p>A recoverable key chain snapshot is considered pending if any of the following conditions 101 * are met: 102 * 103 * <ul> 104 * <li>The system app mutates the key chain. i.e., generates, imports, or removes a key. 105 * <li>The user changes their lock screen. 106 * </ul> 107 * 108 * <p>Whenever the user unlocks their device, if a snapshot is pending, the Recovery Controller 109 * generates a new snapshot. It follows these steps to do so: 110 * 111 * <ul> 112 * <li>Generates a 256-bit AES key using {@link java.security.SecureRandom}. This is the 113 * Recovery Key. 114 * <li>Wraps the key material of all keys in the recoverable key chain with the Recovery Key. 115 * <li>Encrypts the Recovery Key with both the public key of the trusted hardware module and a 116 * symmetric key derived from the user's lock screen. 117 * </ul> 118 * 119 * <p>The controller then writes this snapshot to disk, and uses the {@link PendingIntent} that was 120 * set by the Recovery Agent during initialization to inform it that a new snapshot is available. 121 * The snapshot only contains keys for that Recovery Agent's {@code uid} - i.e., keys the agent's 122 * app itself generated. If multiple Recovery Agents exist on the device, each will be notified of 123 * their new snapshots, and each snapshots' keys will be only those belonging to the same 124 * {@code uid}. 125 * 126 * <p>The Recovery Agent retrieves its most recent snapshot by calling 127 * {@link #getKeyChainSnapshot()}. It syncs the snapshot to the remote server. The snapshot contains 128 * the public key used for encryption, which the server uses to forward the encrypted recovery key 129 * to the correct trusted hardware module. The snapshot also contains the server params, which are 130 * used to identify this device to the server. 131 * 132 * <p>The client uses the server params to identify a device whose key chain it wishes to restore. 133 * This may be on a different device to the device that originally synced the key chain. The client 134 * sends the server params identifying the previous device to the server. The server returns the 135 * X509 certificate identifying the trusted hardware module in which the encrypted Recovery Key is 136 * stored. It also returns some vault parameters identifying that particular Recovery Key to the 137 * trusted hardware module. And it also returns a vault challenge, which is used as part of the 138 * vault opening protocol to ensure the recovery claim is fresh. See the whitepaper for more 139 * details. 140 * 141 * <p>The key chain is recovered via a {@link RecoverySession}. A Recovery Agent creates one by 142 * invoking {@link #createRecoverySession()}. It then invokes 143 * {@link RecoverySession#start(String, CertPath, byte[], byte[], List)} with these arguments: 144 * 145 * <ul> 146 * <li>The alias of the root of trust used to verify the trusted hardware module. 147 * <li>The X509 certificate of the trusted hardware module. 148 * <li>The vault parameters used to identify the Recovery Key to the trusted hardware module. 149 * <li>The vault challenge, as issued by the trusted hardware module. 150 * <li>A list of secrets, corresponding to the secrets used to protect the key chain. At the 151 * moment this is a single {@link KeyChainProtectionParams} containing the lock screen of the 152 * device whose key chain is to be recovered. 153 * </ul> 154 * 155 * <p>This method returns a byte array containing the Recovery Claim, which can be issued to the 156 * remote trusted hardware module. It is encrypted with the trusted hardware module's public key 157 * (which has itself been certified with the root of trust). It also contains an ephemeral symmetric 158 * key generated for this recovery session, which the remote trusted hardware module uses to encrypt 159 * its responses. This is the Session Key. 160 * 161 * <p>If the lock screen provided is correct, the remote trusted hardware module decrypts one of the 162 * layers of lock-screen encryption from the Recovery Key. It then returns this key, encrypted with 163 * the Session Key to the Recovery Agent. As the Recovery Agent does not know the Session Key, it 164 * must then invoke {@link RecoverySession#recoverKeyChainSnapshot(byte[], List)} with the encrypted 165 * Recovery Key and the list of wrapped application keys. The controller then decrypts the layer of 166 * encryption provided by the Session Key, and uses the lock screen to decrypt the final layer of 167 * encryption. It then uses the Recovery Key to decrypt all of the wrapped application keys, and 168 * imports them into its own KeyStore. The Recovery Agent's app may then access these keys by 169 * calling {@link #getKey(String)}. Only this app's {@code uid} may access the keys that have been 170 * recovered. 171 * 172 * @hide 173 */ 174@SystemApi 175public class RecoveryController { 176 private static final String TAG = "RecoveryController"; 177 178 /** Key has been successfully synced. */ 179 public static final int RECOVERY_STATUS_SYNCED = 0; 180 /** Waiting for recovery agent to sync the key. */ 181 public static final int RECOVERY_STATUS_SYNC_IN_PROGRESS = 1; 182 /** Key cannot be synced. */ 183 public static final int RECOVERY_STATUS_PERMANENT_FAILURE = 3; 184 185 /** 186 * Failed because no snapshot is yet pending to be synced for the user. 187 * 188 * @hide 189 */ 190 public static final int ERROR_NO_SNAPSHOT_PENDING = 21; 191 192 /** 193 * Failed due to an error internal to the recovery service. This is unexpected and indicates 194 * either a problem with the logic in the service, or a problem with a dependency of the 195 * service (such as AndroidKeyStore). 196 * 197 * @hide 198 */ 199 public static final int ERROR_SERVICE_INTERNAL_ERROR = 22; 200 201 /** 202 * Failed because the user does not have a lock screen set. 203 * 204 * @hide 205 */ 206 public static final int ERROR_INSECURE_USER = 23; 207 208 /** 209 * Error thrown when attempting to use a recovery session that has since been closed. 210 * 211 * @hide 212 */ 213 public static final int ERROR_SESSION_EXPIRED = 24; 214 215 /** 216 * Failed because the format of the provided certificate is incorrect, e.g., cannot be decoded 217 * properly or misses necessary fields. 218 * 219 * <p>Note that this is different from {@link #ERROR_INVALID_CERTIFICATE}, which implies the 220 * certificate has a correct format but cannot be validated. 221 * 222 * @hide 223 */ 224 public static final int ERROR_BAD_CERTIFICATE_FORMAT = 25; 225 226 /** 227 * Error thrown if decryption failed. This might be because the tag is wrong, the key is wrong, 228 * the data has become corrupted, the data has been tampered with, etc. 229 * 230 * @hide 231 */ 232 public static final int ERROR_DECRYPTION_FAILED = 26; 233 234 /** 235 * Error thrown if the format of a given key is invalid. This might be because the key has a 236 * wrong length, invalid content, etc. 237 * 238 * @hide 239 */ 240 public static final int ERROR_INVALID_KEY_FORMAT = 27; 241 242 /** 243 * Failed because the provided certificate cannot be validated, e.g., is expired or has invalid 244 * signatures. 245 * 246 * <p>Note that this is different from {@link #ERROR_BAD_CERTIFICATE_FORMAT}, which denotes 247 * incorrect certificate formats, e.g., due to wrong encoding or structure. 248 * 249 * @hide 250 */ 251 public static final int ERROR_INVALID_CERTIFICATE = 28; 252 253 private final ILockSettings mBinder; 254 private final KeyStore mKeyStore; 255 256 private RecoveryController(ILockSettings binder, KeyStore keystore) { 257 mBinder = binder; 258 mKeyStore = keystore; 259 } 260 261 /** 262 * Internal method used by {@code RecoverySession}. 263 * 264 * @hide 265 */ 266 ILockSettings getBinder() { 267 return mBinder; 268 } 269 270 /** 271 * Gets a new instance of the class. 272 */ 273 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 274 @NonNull public static RecoveryController getInstance(@NonNull Context context) { 275 ILockSettings lockSettings = 276 ILockSettings.Stub.asInterface(ServiceManager.getService("lock_settings")); 277 return new RecoveryController(lockSettings, KeyStore.getInstance()); 278 } 279 280 /** 281 * @deprecated Use {@link #initRecoveryService(String, byte[], byte[])} instead. 282 */ 283 @Deprecated 284 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 285 public void initRecoveryService( 286 @NonNull String rootCertificateAlias, @NonNull byte[] signedPublicKeyList) 287 throws CertificateException, InternalRecoveryServiceException { 288 throw new CertificateException("Deprecated initRecoveryService method called"); 289 } 290 291 /** 292 * Initializes the recovery service for the calling application. The detailed steps should be: 293 * <ol> 294 * <li>Parse {@code signatureFile} to get relevant information. 295 * <li>Validate the signer's X509 certificate, contained in {@code signatureFile}, against 296 * the root certificate pre-installed in the OS and chosen by {@code 297 * rootCertificateAlias}. 298 * <li>Verify the public-key signature, contained in {@code signatureFile}, and verify it 299 * against the entire {@code certificateFile}. 300 * <li>Parse {@code certificateFile} to get relevant information. 301 * <li>Check the serial number, contained in {@code certificateFile}, and skip the following 302 * steps if the serial number is not larger than the one previously stored. 303 * <li>Randomly choose a X509 certificate from the endpoint X509 certificates, contained in 304 * {@code certificateFile}, and validate it against the root certificate pre-installed 305 * in the OS and chosen by {@code rootCertificateAlias}. 306 * <li>Store the chosen X509 certificate and the serial in local database for later use. 307 * </ol> 308 * 309 * @param rootCertificateAlias the alias of a root certificate pre-installed in the OS 310 * @param certificateFile the binary content of the XML file containing a list of recovery 311 * service X509 certificates, and other metadata including the serial number 312 * @param signatureFile the binary content of the XML file containing the public-key signature 313 * of the entire certificate file, and a signer's X509 certificate 314 * @throws CertificateException if the given certificate files cannot be parsed or validated 315 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 316 * service. 317 */ 318 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 319 public void initRecoveryService( 320 @NonNull String rootCertificateAlias, @NonNull byte[] certificateFile, 321 @NonNull byte[] signatureFile) 322 throws CertificateException, InternalRecoveryServiceException { 323 try { 324 mBinder.initRecoveryServiceWithSigFile( 325 rootCertificateAlias, certificateFile, signatureFile); 326 } catch (RemoteException e) { 327 throw e.rethrowFromSystemServer(); 328 } catch (ServiceSpecificException e) { 329 if (e.errorCode == ERROR_BAD_CERTIFICATE_FORMAT 330 || e.errorCode == ERROR_INVALID_CERTIFICATE) { 331 throw new CertificateException("Invalid certificate for recovery service", e); 332 } 333 throw wrapUnexpectedServiceSpecificException(e); 334 } 335 } 336 337 /** 338 * @deprecated Use {@link #getKeyChainSnapshot()} 339 */ 340 @Deprecated 341 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 342 public @Nullable KeyChainSnapshot getRecoveryData() throws InternalRecoveryServiceException { 343 return getKeyChainSnapshot(); 344 } 345 346 /** 347 * Returns data necessary to store all recoverable keys. Key material is 348 * encrypted with user secret and recovery public key. 349 * 350 * @return Data necessary to recover keystore or {@code null} if snapshot is not available. 351 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 352 * service. 353 */ 354 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 355 public @Nullable KeyChainSnapshot getKeyChainSnapshot() 356 throws InternalRecoveryServiceException { 357 try { 358 return mBinder.getKeyChainSnapshot(); 359 } catch (RemoteException e) { 360 throw e.rethrowFromSystemServer(); 361 } catch (ServiceSpecificException e) { 362 if (e.errorCode == ERROR_NO_SNAPSHOT_PENDING) { 363 return null; 364 } 365 throw wrapUnexpectedServiceSpecificException(e); 366 } 367 } 368 369 /** 370 * Sets a listener which notifies recovery agent that new recovery snapshot is available. {@link 371 * #getKeyChainSnapshot} can be used to get the snapshot. Note that every recovery agent can 372 * have at most one registered listener at any time. 373 * 374 * @param intent triggered when new snapshot is available. Unregisters listener if the value is 375 * {@code null}. 376 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 377 * service. 378 */ 379 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 380 public void setSnapshotCreatedPendingIntent(@Nullable PendingIntent intent) 381 throws InternalRecoveryServiceException { 382 try { 383 mBinder.setSnapshotCreatedPendingIntent(intent); 384 } catch (RemoteException e) { 385 throw e.rethrowFromSystemServer(); 386 } catch (ServiceSpecificException e) { 387 throw wrapUnexpectedServiceSpecificException(e); 388 } 389 } 390 391 /** 392 * Server parameters used to generate new recovery key blobs. This value will be included in 393 * {@code KeyChainSnapshot.getEncryptedRecoveryKeyBlob()}. The same value must be included 394 * in vaultParams {@link RecoverySession#start(CertPath, byte[], byte[], List)}. 395 * 396 * @param serverParams included in recovery key blob. 397 * @see #getKeyChainSnapshot 398 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 399 * service. 400 */ 401 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 402 public void setServerParams(@NonNull byte[] serverParams) 403 throws InternalRecoveryServiceException { 404 try { 405 mBinder.setServerParams(serverParams); 406 } catch (RemoteException e) { 407 throw e.rethrowFromSystemServer(); 408 } catch (ServiceSpecificException e) { 409 throw wrapUnexpectedServiceSpecificException(e); 410 } 411 } 412 413 /** 414 * @deprecated Use {@link #getAliases()}. 415 */ 416 @Deprecated 417 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 418 public List<String> getAliases(@Nullable String packageName) 419 throws InternalRecoveryServiceException { 420 return getAliases(); 421 } 422 423 /** 424 * Returns a list of aliases of keys belonging to the application. 425 */ 426 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 427 public @NonNull List<String> getAliases() throws InternalRecoveryServiceException { 428 try { 429 Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(); 430 return new ArrayList<>(allStatuses.keySet()); 431 } catch (RemoteException e) { 432 throw e.rethrowFromSystemServer(); 433 } catch (ServiceSpecificException e) { 434 throw wrapUnexpectedServiceSpecificException(e); 435 } 436 } 437 438 /** 439 * @deprecated Use {@link #setRecoveryStatus(String, int)} 440 */ 441 @Deprecated 442 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 443 public void setRecoveryStatus( 444 @NonNull String packageName, String alias, int status) 445 throws NameNotFoundException, InternalRecoveryServiceException { 446 setRecoveryStatus(alias, status); 447 } 448 449 /** 450 * Sets the recovery status for given key. It is used to notify the keystore that the key was 451 * successfully stored on the server or that there was an error. An application can check this 452 * value using {@link #getRecoveryStatus(String, String)}. 453 * 454 * @param alias The alias of the key whose status to set. 455 * @param status The status of the key. One of {@link #RECOVERY_STATUS_SYNCED}, 456 * {@link #RECOVERY_STATUS_SYNC_IN_PROGRESS} or {@link #RECOVERY_STATUS_PERMANENT_FAILURE}. 457 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 458 * service. 459 */ 460 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 461 public void setRecoveryStatus(@NonNull String alias, int status) 462 throws InternalRecoveryServiceException { 463 try { 464 mBinder.setRecoveryStatus(alias, status); 465 } catch (RemoteException e) { 466 throw e.rethrowFromSystemServer(); 467 } catch (ServiceSpecificException e) { 468 throw wrapUnexpectedServiceSpecificException(e); 469 } 470 } 471 472 /** 473 * @deprecated Use {@link #getRecoveryStatus(String)}. 474 */ 475 @Deprecated 476 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 477 public int getRecoveryStatus(String packageName, String alias) 478 throws InternalRecoveryServiceException { 479 return getRecoveryStatus(alias); 480 } 481 482 /** 483 * Returns the recovery status for the key with the given {@code alias}. 484 * 485 * <ul> 486 * <li>{@link #RECOVERY_STATUS_SYNCED} 487 * <li>{@link #RECOVERY_STATUS_SYNC_IN_PROGRESS} 488 * <li>{@link #RECOVERY_STATUS_PERMANENT_FAILURE} 489 * </ul> 490 * 491 * @see #setRecoveryStatus(String, int) 492 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 493 * service. 494 */ 495 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 496 public int getRecoveryStatus(@NonNull String alias) throws InternalRecoveryServiceException { 497 try { 498 Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(); 499 Integer status = allStatuses.get(alias); 500 if (status == null) { 501 return RecoveryController.RECOVERY_STATUS_PERMANENT_FAILURE; 502 } else { 503 return status; 504 } 505 } catch (RemoteException e) { 506 throw e.rethrowFromSystemServer(); 507 } catch (ServiceSpecificException e) { 508 throw wrapUnexpectedServiceSpecificException(e); 509 } 510 } 511 512 /** 513 * Specifies a set of secret types used for end-to-end keystore encryption. Knowing all of them 514 * is necessary to recover data. 515 * 516 * @param secretTypes {@link KeyChainProtectionParams#TYPE_LOCKSCREEN} 517 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 518 * service. 519 */ 520 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 521 public void setRecoverySecretTypes( 522 @NonNull @KeyChainProtectionParams.UserSecretType int[] secretTypes) 523 throws InternalRecoveryServiceException { 524 try { 525 mBinder.setRecoverySecretTypes(secretTypes); 526 } catch (RemoteException e) { 527 throw e.rethrowFromSystemServer(); 528 } catch (ServiceSpecificException e) { 529 throw wrapUnexpectedServiceSpecificException(e); 530 } 531 } 532 533 /** 534 * Defines a set of secret types used for end-to-end keystore encryption. Knowing all of them is 535 * necessary to generate KeyChainSnapshot. 536 * 537 * @return list of recovery secret types 538 * @see KeyChainSnapshot 539 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 540 * service. 541 */ 542 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 543 public @NonNull @KeyChainProtectionParams.UserSecretType int[] getRecoverySecretTypes() 544 throws InternalRecoveryServiceException { 545 try { 546 return mBinder.getRecoverySecretTypes(); 547 } catch (RemoteException e) { 548 throw e.rethrowFromSystemServer(); 549 } catch (ServiceSpecificException e) { 550 throw wrapUnexpectedServiceSpecificException(e); 551 } 552 } 553 554 /** 555 * Deprecated. 556 * Generates a AES256/GCM/NoPADDING key called {@code alias} and loads it into the recoverable 557 * key store. Returns the raw material of the key. 558 * 559 * @param alias The key alias. 560 * @param account The account associated with the key 561 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 562 * service. 563 * @throws LockScreenRequiredException if the user has not set a lock screen. This is required 564 * to generate recoverable keys, as the snapshots are encrypted using a key derived from the 565 * lock screen. 566 */ 567 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 568 public byte[] generateAndStoreKey(@NonNull String alias, byte[] account) 569 throws InternalRecoveryServiceException, LockScreenRequiredException { 570 throw new UnsupportedOperationException("Operation is not supported, use generateKey"); 571 } 572 573 /** 574 * @deprecated Use {@link #generateKey(String)}. 575 */ 576 @Deprecated 577 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 578 public Key generateKey(@NonNull String alias, byte[] account) 579 throws InternalRecoveryServiceException, LockScreenRequiredException { 580 return generateKey(alias); 581 } 582 583 /** 584 * Generates a recoverable key with the given {@code alias}. 585 * 586 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 587 * service. 588 * @throws LockScreenRequiredException if the user does not have a lock screen set. A lock 589 * screen is required to generate recoverable keys. 590 */ 591 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 592 public @NonNull Key generateKey(@NonNull String alias) throws InternalRecoveryServiceException, 593 LockScreenRequiredException { 594 try { 595 String grantAlias = mBinder.generateKey(alias); 596 if (grantAlias == null) { 597 throw new InternalRecoveryServiceException("null grant alias"); 598 } 599 return getKeyFromGrant(grantAlias); 600 } catch (RemoteException e) { 601 throw e.rethrowFromSystemServer(); 602 } catch (UnrecoverableKeyException e) { 603 throw new InternalRecoveryServiceException("Failed to get key from keystore", e); 604 } catch (ServiceSpecificException e) { 605 if (e.errorCode == ERROR_INSECURE_USER) { 606 throw new LockScreenRequiredException(e.getMessage()); 607 } 608 throw wrapUnexpectedServiceSpecificException(e); 609 } 610 } 611 612 /** 613 * Imports a 256-bit recoverable AES key with the given {@code alias} and the raw bytes {@code 614 * keyBytes}. 615 * 616 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 617 * service. 618 * @throws LockScreenRequiredException if the user does not have a lock screen set. A lock 619 * screen is required to generate recoverable keys. 620 * 621 */ 622 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 623 public @NonNull Key importKey(@NonNull String alias, @NonNull byte[] keyBytes) 624 throws InternalRecoveryServiceException, LockScreenRequiredException { 625 try { 626 String grantAlias = mBinder.importKey(alias, keyBytes); 627 if (grantAlias == null) { 628 throw new InternalRecoveryServiceException("Null grant alias"); 629 } 630 return getKeyFromGrant(grantAlias); 631 } catch (RemoteException e) { 632 throw e.rethrowFromSystemServer(); 633 } catch (UnrecoverableKeyException e) { 634 throw new InternalRecoveryServiceException("Failed to get key from keystore", e); 635 } catch (ServiceSpecificException e) { 636 if (e.errorCode == ERROR_INSECURE_USER) { 637 throw new LockScreenRequiredException(e.getMessage()); 638 } 639 throw wrapUnexpectedServiceSpecificException(e); 640 } 641 } 642 643 /** 644 * Gets a key called {@code alias} from the recoverable key store. 645 * 646 * @param alias The key alias. 647 * @return The key. 648 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 649 * service. 650 * @throws UnrecoverableKeyException if key is permanently invalidated or not found. 651 */ 652 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 653 public @Nullable Key getKey(@NonNull String alias) 654 throws InternalRecoveryServiceException, UnrecoverableKeyException { 655 try { 656 String grantAlias = mBinder.getKey(alias); 657 if (grantAlias == null || "".equals(grantAlias)) { 658 return null; 659 } 660 return getKeyFromGrant(grantAlias); 661 } catch (RemoteException e) { 662 throw e.rethrowFromSystemServer(); 663 } catch (ServiceSpecificException e) { 664 throw wrapUnexpectedServiceSpecificException(e); 665 } 666 } 667 668 /** 669 * Returns the key with the given {@code grantAlias}. 670 */ 671 @NonNull Key getKeyFromGrant(@NonNull String grantAlias) throws UnrecoverableKeyException { 672 return AndroidKeyStoreProvider.loadAndroidKeyStoreKeyFromKeystore( 673 mKeyStore, 674 grantAlias, 675 KeyStore.UID_SELF); 676 } 677 678 /** 679 * Removes a key called {@code alias} from the recoverable key store. 680 * 681 * @param alias The key alias. 682 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 683 * service. 684 */ 685 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 686 public void removeKey(@NonNull String alias) throws InternalRecoveryServiceException { 687 try { 688 mBinder.removeKey(alias); 689 } catch (RemoteException e) { 690 throw e.rethrowFromSystemServer(); 691 } catch (ServiceSpecificException e) { 692 throw wrapUnexpectedServiceSpecificException(e); 693 } 694 } 695 696 /** 697 * Returns a new {@link RecoverySession}. 698 * 699 * <p>A recovery session is required to restore keys from a remote store. 700 */ 701 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 702 public @NonNull RecoverySession createRecoverySession() { 703 return RecoverySession.newInstance(this); 704 } 705 706 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 707 public @NonNull Map<String, X509Certificate> getRootCertificates() { 708 return TrustedRootCertificates.getRootCertificates(); 709 } 710 711 InternalRecoveryServiceException wrapUnexpectedServiceSpecificException( 712 ServiceSpecificException e) { 713 if (e.errorCode == ERROR_SERVICE_INTERNAL_ERROR) { 714 return new InternalRecoveryServiceException(e.getMessage()); 715 } 716 717 // Should never happen. If it does, it's a bug, and we need to update how the method that 718 // called this throws its exceptions. 719 return new InternalRecoveryServiceException("Unexpected error code for method: " 720 + e.errorCode, e); 721 } 722} 723